The Schottky diode (named after German physicist Walter H. Schottky) is a well-known semiconductor diode device that is achieved using a metal-semiconductor junction, frequently referred to as a Schottky barrier, in contrast to an ordinary p-n junction of a conventional semiconductor diode. A Schottky diode is characterized by a low forward voltage drop (e.g., 0.1-0.4 V) and very fast switching action due to the almost nonexistent depletion width in the metal. Schottky diodes find application in a variety of power devices including switched-mode power supplies and power converters.
A type of Schottky rectifier structure called a Trench MOS Barrier Schottky (TMBS) rectifier is commonly used in applications requiring a breakdown voltage (BV) in the range of 100 V-200 V. High-voltage Schottky diodes having a BV higher than −300V are typically designed by connecting multiple lower voltage Schottky diodes (e.g., TMBS structures) in series. This is due to the fact that monolithically integrated (i.e., on a single semiconductor die) Schottky diodes with a BV greater than, say, 200 V, are problematic to manufacture. One difficulty lies in adequately shielding the Schottky junction from the high reverse bias voltage in the off-state. Inadequate shielding of the Schottky junction causes high leakage current under reverse bias conditions. In addition, stacking a series of TMBS devices to create a Schottky diode with a BV greater than ˜300 V is very costly.